Cognitive imitation in rhesus macaques

Experiments on imitation typically evaluate a student's ability to copy some feature of an expert's motor behavior. Here, we describe a type of observational learning in which a student copies a cognitive rule rather than a specific motor action. Two rhesus macaques were trained to respond, in a prescribed order, to different sets of photographs that were displayed on a touch-sensitive monitor. Because the position of the photographs varied randomly from trial to trial, sequences could not be learned by motor imitation. Both monkeys learned new sequences more rapidly after observing an expert execute those sequences than when they had to learn new sequences entirely by trial and error.     

Thyroxine: effects of neonatal administration on maturation, development, and behavior

Thyroxine was administered to infant rats within the first 3 days of postnatal life; controls receiving 0.01N NaOH were from the same litter. Thyroxine accelerated the maturation of the pituitary-adrenal response to elec tric shock. The "startle response" ap peared earlier in the experimental ani mals, as did the development and re sponse of the electroencephalogram to novel stimuli. The thyroxine-treated rats, when 16 to 18 days old, acquired a conditioned-avoidance response faster than did controls.     

Transgenic plants as tools to study the molecular organization of plant genes

Transgenic plants are generated in nature by Agrobacterium tumefaciens, a pathogen that produces disease through the transfer of some of its own DNA into susceptible plants. The genes are carried on a plasmid. Much has been learned about how the plasmid is transferred, how the plasmid-borne genes are organized, regulated, and expressed, and how the bacteria's pathogenic effects are produced. The A. tumefaciens plasmid has been manipulated for use as a general vector for the transfer of specific segments of foreign DNA of interest (from plants and other sources) into plants; the activities of various genes and their regulation by enhancer and silencer sequences have been assessed. Future uses of the vector (or others like it that have different host ranges) by the agriculture industry are expected to aid in moving into vulnerable plants specific genes that will protect them from such killers as nonselective herbicides, insects, and viruses.     

Observational learning and social facilitation in the rat

Learning by rats was facilitated when response-relevant cues were provided by other rats; learning increased as a function of number of cues provided. These results suggest that rats can learn by imitation. Learning by rats that observed conspecifics not emitting response-relevant cues was retarded compared to learning by rats that did not observe conspecifics. This indicates that a conspecific's presence can also inhibit learning, a result consistent with social facilitation theory.     

Maternal and environmental influences on the adrenocortical response to stress in weanling rats

Handling rat pups either for 10 or 20 days after birth resulted in a reduction of adrenocortical steroids in the plasma at weaning after the pups were exposed to novel stimuli as compared with controls that were not handled. Nonhandled offspring of mothers which had been handled in infancy also show a reduction in plasma steroids in response to novel stimuli when compared to nonhandled weanling rats of nonhandled mothers. Handling of the offspring when they are infants appears to counteract the influence of the experience of the mother during her infancy.     

The primate hippocampal formation: evidence for a time-limited role in memory storage

Clinical and experimental studies have shown that the hippocampal formation and related structures in the medial temporal lobe are important for learning and memory. Retrograde amnesia was studied prospectively in monkeys to understand the contribution of the hippocampal formation to memory function. Monkeys learned to discriminate 100 pairs of objects beginning 16, 12, 8, 4, and 2 weeks before the hippocampal formation was removed (20 different pairs at each time period). Two weeks after surgery, memory was assessed by presenting each of the 100 object pairs again for a single-choice trial. Normal monkeys exhibited forgetting; that is, they remembered recently learned objects better than objects learned many weeks earlier. Monkeys with hippocampal damage were severely impaired at remembering recently learned objects. In addition, they remembered objects learned long ago as well as normal monkeys did and significantly better than they remembered objects learned recently. These results show that the hippocampal formation is required for memory storage for only a limited period of time after learning. As time passes, its role in memory diminishes, and a more permanent memory gradually develops independently of the hippocampal formation, probably in neocortex.     

农业专家系统中分类产生式规则的知识表示方法

鉴于农业专家系统中的知识多来自于专家经验,且知识规则的表示量非常大的特点,在系统开发中提出采用一种称为“分类产生式规则”的知识表示方法用于农业专家系统,该方法实质性地改进了传统的产生式规则知识表示方法,可以有效地解决基于规则的专家系统存在的知识组合爆炸和搜索匹配费用高的问题。详细介绍了该方法在系统开发中的具体应用,如定义、表示形式和具体推理模型及策略等问题。     

Mining simulation data by rule induction to determine critical source areas of stream water pollution by herbicides

Modelling in environmental sciences is becoming increasingly complex because ever-increasing numbers of processes are combined, thus making model-based decision aids both more relevant but more difficult to develop. Our approach focused on water quality and aimed to identify spatial tree patterns that represent surface flow and pollutant pathways from plot to plot involved in water pollution by herbicides. First, a simulation model predicted herbicide transfer rate, the proportion of applied herbicide that reaches water courses, based on the spatial and temporal distribution of weed-control activities. These predictions were used as a set of learning examples for symbolic learning techniques to induce rules based on qualitative and quantitative attributes and explain two classes of transfer rate. In this study we compared two automatic symbolic learning techniques applied to a set of simulations: (1) a relational-inductive method using the inductive logic programming (ILP) approach to induce spatial tree patterns; and (2) an attribute-value method to induce aggregated attributes of the trees. Twenty-eight and thirty-three rules were learnt by the ILP and attribute-value approaches which explained 81% and 88% of the examples, respectively. The ILP approach provided relevant indicators of plot-to-plot connectivity. The integrated attribute-value approach is simpler and quicker, but the ILP patterns are more useful for stakeholders.     

Instrumental learning of vasomotor responses by rats: learning to respond differentially in the two ears

Curarized and artificially respirated rats were rewarded by electrical stimulation of the brain for changes in the balance of vasomotor activity between the two ears. They learned vasomotor responses in one ear that were independent of those in the other ear, in either forepaw, or in the tail, or of changes in heart rate or temperature. In addition to implications for learning theory and psychosomatic medicine, these results indicate a greater specificity of action in the sympathetic nervous system than is usually attributed to it.     

近1O年篮球规则的演进对技战术的影响

采用文献资料法、专家访谈法、理论分析法等对近10年规则的演变进行分析研究,结果表明：从空间规则演变看,现在篮球的发展趋势是“内外兼顾”,有效促进高大队员全面技术,应加强防守和进攻的提高。从违犯规则演变的方面看,各级裁判员应重视规则的学习,加强对违犯规则的理解,从而在临场执裁中发挥积极作用。     

Building neural representations of habits

Memories for habits and skills ("implicit or procedural memory") and memories for facts ("explicit or episodic memory") are built up in different brain systems and are vulnerable to different neurodegenerative disorders in humans. So that the striatum-based mechanisms underlying habit formation could be studied, chronic recordings from ensembles of striatal neurons were made with multiple tetrodes as rats learned a T-maze procedural task. Large and widely distributed changes in the neuronal activity patterns occurred in the sensorimotor striatum during behavioral acquisition, culminating in task-related activity emphasizing the beginning and end of the automatized procedure. The new ensemble patterns remained stable during weeks of subsequent performance of the same task. These results suggest that the encoding of action in the sensorimotor striatum undergoes dynamic reorganization as habit learning proceeds.     

Auditory information from subcortical electrical stimulation in cats

Animals trained to respond to sound stimuli were found to perform the learned response when they were electrically stimulated through electrodes chronically implanted in subcortical structures of the auditory pathway. Other animals trained to respond to electrical stimulation of subcortical auditory structures showed differential transfer effects depending on the positions of the stimulating electrodes.     

Rats smell in stereo

It has been hypothesized that rats and other mammals can use stereo cues to localize odor sources, but there is limited behavioral evidence to support this hypothesis. We found that rats trained on an odor-localization task can localize odors accurately in one or two sniffs. Bilateral sampling was essential for accurate odor localization, with internasal intensity and timing differences as directional cues. If the stimulus arrived at the correct point of the respiration cycle, internasal timing differences as short as 50 milliseconds sufficed. Neuronal recordings show that bulbar neurons responded differentially to stimuli from the left and stimuli from the right.     

Toward a universal law of generalization for psychological science

A psychological space is established for any set of stimuli by determining metric distances between the stimuli such that the probability that a response learned to any stimulus will generalize to any other is an invariant monotonic function of the distance between them. To a good approximation, this probability of generalization (i) decays exponentially with this distance, and (ii) does so in accordance with one of two metrics, depending on the relation between the dimensions along which the stimuli vary. These empirical regularities are mathematically derivable from universal principles of natural kinds and probabilistic geometry that may, through evolutionary internalization, tend to govern the behaviors of all sentient organisms.     

Calcium-mediated reduction of ionic currents: a biophysical memory trace

Learning behavior similar to vertebrate classical conditioning was demonstrated for the mollusc Hermissenda crassicornis. Postsynaptic membrane changes within well-defined neural systems that mediate the learning play a casual role in recording the learned association for later recall. Specific ionic currents in neural tissue undergo transformations lasting days after associative training with physiologic stimuli. During acquisition the intracellular calcium increases; this increase is accompanied by specific potassium current reduction that lasts for days after conditioning. The increase of calcium enhances calmodulin-dependent phosphorylation of proteins that either regulate or are part of ion channels. These currents and the conditions that precede their transformation occur in many types of vertebrate neurons, and hence this biophysical basis of Hermissenda learning could have relevance for species other than the gastropod studied.     

Zn2+ 胁迫对麦长管蚜种群生态遗传学的影响

【目的】研究不同浓度Zn2+处理下,麦长管蚜Sitobion avenae生态遗传学参数、抗氧化酶活性和蛋白质含量的变化,为研究种群暴发、综合防治、重金属毒性效应的分子机理及重金属对昆虫种群遗传进化的影响提供理论依据。【方法】用不同浓度Zn2+(0(对照),2.5,5.0,10.0mmol/L)浇灌小麦幼苗,在其叶片上饲养麦长管蚜及其后代,制作F1、F2、F3代的特定时间生命表,分析重金属Zn2+对麦长管蚜生态遗传学参数、抗氧化酶活性和体内蛋白质含量的影响。【结果】Zn2+处理后,麦长管蚜的世代周期在低浓度(2.5mmol/L)时较对照延长,高浓度时(5.0~10.0mmol/L)则较对照显著缩短;种群净增殖率、内禀增长率和周限增长率均显著低于对照,且随Zn2+浓度的增加而降低。Zn2+对麦长管蚜的过氧化氢酶(CAT)活性有抑制作用,10.0mmol/L Zn2+处理后,CAT活性显著低于对照和2.5mmol/L Zn2+处理;过氧化物酶(POD)活性在各代麦长管蚜之间存在显著差异;2.5mmol/L Zn2+处理后,超氧化物歧化酶(SOD)活性较对照显著升高,而5.0和10.0mmol/L Zn2+处理蚜虫后,SOD活性较对照显著降低;除2.5mmol/L Zn2+处理的F1代外,F1、F2、F3的羧酸酯酶(CarE)活性均高于对照。Zn2+处理后,麦长管蚜体内蛋白质含量明显高于对照,不同浓度Zn2+对蛋白质含量的影响显著;F1、F2、F3代麦长管蚜体内的蛋白质含量平均值分别为37.1,42.9,47.9μg/mg,且差异显著。【结论】Zn2+对麦长管蚜的毒害已遗传给后代并在后代中累积,高浓度Zn2+处理的毒害作用比低浓度Zn2+处理强。     

疲劳累积损伤规律研究综述

疲劳累积损伤规律是疲劳研究中的关键问题之一.现有疲劳累积损伤规律可分为四类,即线性疲劳累积损伤理论、双线性疲劳累积损伤理论、非线性疲劳累积损伤理论和概率疲劳累积损伤理论.每一类理论都有代表性的模型,并各有其优缺点.寻找一个统一的既简单又符合实际损伤发展的疲劳累积损伤规律还是目前疲劳研究中的一个重要课题.     

浅谈英语在法语学习中的负迁移

由于英法两国以往深刻的历史渊源,英语和法语两门语言之间有着千丝万缕的联系。 对于已经学过英语这一语言的学生而言,学习法语的过程中会发生正迁移和负迁移两种现象。 本文将具体分析英语在法语学习过程当中所产生的负迁移,提出相应的解决办法,以期给法语 学习者一定的参考。     

Single neurons in the monkey hippocampus and learning of new associations

The medial temporal lobe is crucial for the ability to learn and retain new declarative memories. This form of memory includes the ability to quickly establish novel associations between unrelated items. To better understand the patterns of neural activity during associative memory formation, we recorded the activity of hippocampal neurons of macaque monkeys as they learned new associations. Hippocampal neurons signaled learning by changing their stimulus-selective response properties. This change in the pattern of selective neural activity occurred before, at the same time as, or after learning, which suggests that these neurons are involved in the initial formation of new associative memories.